1. Field of the Invention
The invention relates to etching equipment utilized, for example, in the manufacture of semiconductor devices. The invention provides improved etching chambers and etching systems which are simpler to manufacture and maintain, and which can be easily modified if desired.
2. Discussion of the Background
Etching equipment is utilized in the manufacture of integrated circuits and other electrical devices. In a typical etching system, workpieces such as semiconductor wafers are retrieved from a wafer cassette by a robot arm which is located in a transfer chamber. The robot arm then transfers the wafers to one or more etching chambers which are disposed about the transfer chamber. Although such systems have long been in use, they are typically complex to manufacture, assemble and maintain. Moreover, prior systems can be limited in their ability to be modified, particularly in a relatively short period of time. For example, sometimes it can be desirable to replace one or more of the chambers of a given system with a different type of etch chamber, for example, to modify the fabrication line, or to replace an older model chamber with an updated model. Thus, the chambers of a system could be replaced with a new chamber, or a line could be reconfigured by exchanging chambers between or among different systems. However, replacement of a chamber is quite cumbersome, requiring awkward equipment, such as a Johnson bar, to lift, move and position a chamber in place such that the chamber can be connected to the transfer chamber as well as various frame components. Further, prior systems have included a number of complex components including, for example, a complex drive assembly for raising and lowering the lower electrode (which holds a wafer during etching) and a complex cooling system for the lower electrode. Such systems are not only more complicated to manufacture, but also can be less reliable or, at least, require more labor to ensure proper operation.
A further shortcoming with existing systems is that an excessive number of parts are often required, thus complicating the manufacture and assembly of etching chambers and systems, and making system modifications more difficult. For example, in the past, a given chamber has been particularly adapted to be located at a specific side or location with respect to the transfer chamber, e.g., the left side, while another chamber was particularly adapted for fitting to the right side of the transfer chamber. Such an arrangement not only complicates the manufacture of the chambers, since a larger number of parts must be manufactured and maintained in inventory, but also, the systems are less flexible in their ability to be modified, for example, if a semiconductor fabrication facility desires to replace or exchange chambers, since the replacement or exchange is limited by the right hand/left hand mountings of the chambers.
Certain etching chambers also utilize a magnet assembly which rotates about the chamber and imparts a magnetic field to the plasma within the chamber. In the past, the magnet assembly has been rotatably mounted on top of a bearing assembly to support the magnets for rotation. Such an arrangement has been recognized as disadvantageous in that the height of the chamber must be increased to accommodate the height of not only the magnets but also the bearing assembly. The increased height of the chamber makes access to the chamber more cumbersome (since chambers are typically accessed for maintenance through the top of the chamber) and also, the drive for the lower electrode must have a sufficient stroke length to raise the wafer up into the desired position within the magnets for etching.
Accordingly, it is desired to provide simplified etching systems and etching chambers, which are easier to manufacture, maintain, use and, if desired, to modify.
It is an object of the invention to provide an etching system which is simpler to manufacture, assemble and maintain.
It is a further object of the invention to provide an etching system in which the system is more readily modifiable, for example, if it is desirable to reconfigure a system or fabrication line by replacing the chambers of the system or by exchanging chambers between/among systems.
It is a further object of the invention to provide an etching system and etching chamber in which the components are simplified, more reliable, and/or easier to use.
It is a further object of the invention to provide an etching system having a reduced footprint (i.e., reduced floor space requirements), and in which components of the system are more easily accessible for maintenance and inspection.
These and other objects and advantages are achieved in accordance with the present invention in which an etching system is provided having a plurality of etching chambers disposed about a transfer chamber. In accordance with one aspect of the invention, the chambers are unisex or ambidextrous. In other words, the same chamber can be mounted at various locations about the transfer chamber. Accordingly, different chambers are not needed for different sites about the transfer chamber. As a result, different system configurations are more readily achieved (i.e., chambers can be more conveniently replaced or exchanged), and the number of parts required to manufacture the etching system (and chambers of the system) is decreased.
In accordance with a further aspect of the invention, the chambers are more modularized. In other words, the chambers can be more readily positioned and coupled to the transfer chamber. As a result, the assembly of the system is simplified, and reconfiguration of a system (e.g., replacing one type of chamber with another type of chamber) can be performed more quickly and conveniently. In addition, if a chamber is defective or in need of repair, the chamber can be quickly replaced with a chamber of the same type.
Further, in accordance with the invention, various components of the system and chambers are improved and simplified. In accordance with one aspect, the drive assembly which raises and lowers the lower electrode is simplified. The new drive assembly is advantageous in that it requires less space than prior arrangements. Further, an improved and simplified back cooling system is provided. The system is improved in that the components of the system, except for the supply source of the heat transfer medium, are located below the lower electrode. In the past, control components of the system were disposed either on the frame of the etching system or in a utilities cabinet. Such a prior system was not only complex in that a larger number of control devices were required, but also the cooling system was more difficult to control, since the coolant was controlled more remotely from the location at which the required cooling takes place. Thus, the system was slower to respond to required changes in the flow of the heat transfer medium.
By mounting the wafer back cooling system components below the lower electrode and for movement with the lower electrode, the cooling system is simplified and responds more quickly to changes required in the gas flow rate of the system. The improved cooling system and drive system are particularly advantageous in combination, since the placement of the cooling system below the lower electrode is more easily achieved with the simplified drive arrangement of the invention.
The invention further provides additional improvements in system and chamber components. For example, an improved mounting arrangement for rotatably mounting a rotating magnet assembly is provided which reduces the height of the chamber, and thus reduces the stroke of the drive required for the lower electrode. The reduced stroke is also advantageous in that the product throughput can be increased, since the time required for the drive to complete a stroke is reduced. Further, the reduced height provides for more convenient access to the chamber for maintenance or repair.
In accordance with a further aspect of the invention, an improved assembly is provided for opening the lid of the respective chambers. This lid mounting assembly is more convenient to use and is also safer than prior arrangements.